The present applicant had previously disclosed on-window MEMs heaters, wherein the device has a membrane region that is heatable and imagable, allowing the user to heat and image a sample in real time with increased accuracy. Disadvantageously, larger conductive samples or fluid reservoirs, i.e., environmental cells, require an increased power, thermal stability under different conditions of fluid flow, thermal uniformity, and electrical isolation not achievable with on-window MEMs heaters. Accordingly, a device comprising heater elements is needed for heating enclosed fluid reservoirs or heating larger conductive samples inside of an electron microscope.
Typical bulk heaters cannot be patterned onto the MEMs sample support and are usually a separate component. These bulk heaters are not easily serviceable and are typically further removed from the sample position requiring more power output than necessary and increased sample drift during imaging due to more thermal expansion. Being further removed from the sample position the heater is not very responsive to sample temperature and the element impedance cannot be used as a reliable sensor of sample temperature.
U.S. Patent Application Publication No. 20080179518 in the name of Creemer et al. relates in part to an on-window heating coil solution. Creemer et al. placed the heating coils in the middle of the observation window only, which will locally heat the fluid around the heating coils but there will also be significant thermal degradation further away from the coils. Creemer et al. does not conduct thermal energy into the support frame of their device. Another disadvantage of the Creemer et al. application is that with an on-membrane heater, the stresses on the membrane are considerably more.
Accordingly, a device is needed that provides the power, thermal stability and uniformity, and electrical isolation of a typical bulk heater as well as the proximity, serviceability, thermal response, and wafer scale benefits of a MEMs heater.